Bosch boiler installation kit with dirt separator - polyphosphate dispenser - condensate neutraliser - double flue gas outletIVAR MAGNETIC DIRTSTOP EASY 3 4 F x 3 4 M UNDER BOILER FOR CONDENSING BOILER Code 520360 The dirt separator is a device used in heating systems with condensing boilers and performs the important function of protecting the boiler. It is installed on the return of the heating circuit before the water re enters the boiler and retains the impurities present in the circuit which would otherwise damage the exchanger and the other components of the boiler.